VF-121 (Fighter Squadron 121) of the US Navy was a former Pacific Fleet Replacement Air Group (RAG) unit that, by the time of its disestablishment (30 September 1980). Originally established as VF-781, a reserve squadron on 2 August 1950, it was redesignated as VF-121 on 4 February 1953 and disestablished on 30 September 1980.[1] On 11 April 1958 changed duty from Fleet Squadron to the Fleet Replacement Squadron and was later was charged with the training of Navy F-4 Phantom flight and maintenance crews.

VF-781 served on board USS Bon Homme Richard (CV-31) with Air Group 102 (CVG-102) flying F9F-2B Panthers from May 10, 1951 to December 17, 1951. VF-781's next cruise was on board USS Hancock (CV-19) flying with Air Group 102(CVG-102). The Pacemakers flew F9F-5's in Korea from September 15, 1952 to May 18, 1953. The first F9F-5s entered combat in October 1952 with VF-781 and VF-783 from USS Hancock. In November 18, 1952, VF-781 scored its first MiG-15 kills by Elmer Royce Williams, John Middleton and Rowlans by 20mm guns in the F9F-5's.

VF-781 was re-designated VF-121 on February 4, 1953. VF-781 originally flew F4U Corsairs then transition to F9F-2/-5 Panthers. After re-designation to VF-121, the squadron transitioned to F9F-6 Cougars with commanding officer Jimmie E Savage for their 1954 deployment on the USS Boxer. They made two more cruises to the Western Pacific and Korea on the USS Hancock from 10 Aug 1955 to 15 Mar 1956 with CVG-12 flying F9F-8, with the tail code of 'D' then converted to FJ-3 Fury's. The last cruise was on board USS Lexington from April 19, 1957 to October 17, 1957.

Commander R. E. 'Dusty' Rhodes was CO of VF-121 during 1955. Cdr. Rhodes worked with VC-6 and their AJ Savage tankers on air-to-air refueling. The exercise was successfully off the coast of San Diego, Ca. Cdr. Rhodes was a former Commanding Officer of the Blue Angels flight team from 1947 to 1950.[2]

The first West Coast F4H Phantom Squadron was assigned to VF-121 at NAS Miramar, Ca. VF-121 Pacemakers received the first examples of F-4B Phantoms at NAS Miramar in 1961.[3] On 24 May 1961, Project LANA- a 50th Anniversary of Naval Aviation Transcontinental Race for the Bendix Trophy, was won by a VF-121 crew.
Aircrews came from other aircraft types and became qualified in the flight, navigation and operation of the F4H Phantom. Maintainers came from other squadrons and 'A' schools to learn the Phantom as well. Gunnery and weapons training was obtained while deployed to MCAS Yuma, AZ. Carrier Field Landing Practice (FCLP). Their skills were graded by a Landing Signals Office (LSO) the same way as on a carrier. Once qualified they could advance to actual carrier day/ night launch/ recovery qualifications. After this training the aircrews were assigned to a fleet squadron and sea duty.